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Visible fluorescence spectroscopy of single proteins at liquid-helium temperature
Satoru Fujiyoshi1, Masanori Fujiwara, Michio Matsushita
1Department of Physics, Tokyo Institute of Technology and CREST/JST, Tokyo, 152-8551, Japan. fujiyoshi@phys.titech.ac.jp
Abstract:
Fluorescence spectroscopy of single proteins at liquid-helium temperatures reveals a relation between structural dynamics and biological functions of the proteins. The technical difficulties in detecting visible fluorescence are chromatic aberration and optical background. They were overcome by a new optical design using reflective optics and employing two-photon excitation. The fluorescence spectrum of single green-fluorescent proteins taken at a temperature of 1.5 K makes a distinction between different metastable conformations that last for tens of seconds.
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